1. Field of Invention
This document describes a technology for painting and image printing that utilizes a simple system with multiple colorants and a single printing head through which the image is printed by a transparent ink or binder. The primary area of interest involves dry pigments of larger molecular weight colorants, such as cholesteric liquid crystal (CLC) pigments, and their diverse applications in modern printing and painting. In addition, new techniques can be easily expanded to serve more functions, such as 3-D stereoscopic image capability.
2. Brief Description of the Literature
Broadband reflecting polarizers were introduced in application Ser. No. 08/550,022 (now U.S. Pat. No. 5,691,789) entitled xe2x80x9cSingle Layer Reflective Super Broadband Circular Polarizer and Method of Fabrication Thereforxe2x80x9d by Sadeg M. Faris and Le Li which was filed Oct. 30, 1995. Such broadband polarizers are made by producing a single layer having cholesteric liquid crystal order where the pitch of the liquid crystal order varies in a non linear fashion across the layer.
General references on polymer dispersed liquid crystals may be found in detail in xe2x80x9cPolymer Dispersed Liquid crystal displaysxe2x80x9d, by J. W. Doane, a chapter in xe2x80x9cLiquid Crystalsxe2x80x9d, Ed. B. Bahadur, World Scientific Publishing, Singapore, and xe2x80x9cCLC/polymer dispersion for haze-free light shutters, by D. Yang et al. Appl. Phys. Lett. 60, 3102 (1992).
Since the early attempt of utilizing cholesteric film as optical filters and the effort on polymer encapsulated nematic liquid crystals for display, much attention has been focused on trying to bring polymeric liquid crystals and cholesteric liquid crystals together to make devices for light control application. (See, for example J. Adams, W. Hass, J. Dailey, Journal of Applied Physics, 1971, and J. L. Fergason, Society for Information Display Digest, 1985.). The above identified U.S. patents and other references are hereby incorporated by reference .
In modern society, information exchange plays an important role. Efficient methods to convey information rely on high-quality communication devices. Among them, printing and painting devices are becoming more and more important. Currently, ink-jet, bubble jet, and laser printing, along with off-set, flexo press, and screen printing are universally used. All of these printing techniques possess a common feature. In order to perform color printing, multiple nozzles or screens must be used for cyan, magenta, yellow and black colorants. This forces the printing system to become mechanically complex and limits the system from being able to be expanded to serve multiple functions such as the case of 3-D printing. In addition, since the printing nozzles and screens have a very fine apertures, they can""t handle those colorants with relatively larger pigment particles.
Furthermore, it has been known that CLC can be used as a colorant for painting and printing because of their excellent spectral characteristics and wide color range properties. However, special techniques must be employed in order to use CLC. Special surface treatments and curing methods are all necessary to print and dry CLC films. As a result, CLC has never been practically used in real artwork or other applications. However, the present invention of the new CLC ink based on CLC pigment solves all these problems at once. No special surface treatment and curing equipment is required to dry and/or cure the colorant. Another benefit is the capability of generating colorful 3-D stereoscopic images since the CLC ink reflects polarized light.
One objective of this invention is to improve today""s printing technologies. The inventors of the present invention have developed a new printing technology that offers a simple system configuration, greater flexibility, improved printing quality, and enhanced functionality. The new technique is termed Dry Printing Technology (DPT) by its working principle. It uses only one printing head and prints images with an invisible ink. It can handle, in principle, all kinds of colorants, even colorants with larger pigments so that it removes the pigment size constraint in ink jet nozzle printing. By adopting a new printing head combined with CLC pigments, dry printing offers enhanced image quality. Finally, DPT can be easily expanded to print a colorful picture in 3-D with the CLC pigments.
Another objective is the application of the invented printing technique using a newly developed, novel colorant to achieve unique display effects that usual technologies do not possess. The ink is made from CLC pigments mixed into a suitable optically clear carrier.
Yet another objective is to give printing devices more flexibility and enhance their functionality.
Yet another objective is to achieve a special visual effect of objects which appear to have different colors depending on the viewing angle.
Yet another objective is to create 3-D stereoscopic images in full color at any size.
Yet another objective is to provide security printing
Yet another objective is to provide unique cosmetic effects.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considering in conjunction with the accompanying drawings.
The present invention provides a method of using flat flakes of non metallic reflecting pigment by applying the flakes to a surface and ensuring that the flakes lie substantially parallel to the surface. A binder material may first be adhered to the surface in a pattern or uniformly. The flakes are applied to the surface, and stick where the binder has been prepared. The flakes are applied so that they lie parallel to the surface, or the flakes are applied, then rolled or buffed to align them parallel to the surface. If the flakes are CLC flakes, multilayer polymer flakes, or multilayer inorganic material flakes, an iridescent film which changes color with viewing angle may be produced.